package lib.com.sun.media.sound;

import java.util.ArrayList;

import lib.sound.midi.*;


// TODO:
// - define and use a global symbolic constant for 60000000 (see convertTempo)

/**
 * Some utilities for MIDI (some stuff is used from july.sound.midi)
 *
 * @version %I%, %E%
 * @author Florian Bomers
 */
public class MidiUtils {

    public final static int DEFAULT_TEMPO_MPQ = 500000; // 120bpm
    public final static int META_END_OF_TRACK_TYPE = 0x2F;
    public final static int META_TEMPO_TYPE = 0x51;


    /** return true if the passed message is Meta End Of Track */
    public static boolean isMetaEndOfTrack(MidiMessage midiMsg) {
    // first check if it is a META message at all
    if (midiMsg.getLength() != 3
        || midiMsg.getStatus() != MetaMessage.META) {
        return false;
    }
    // now get message and check for end of track
    byte[] msg = midiMsg.getMessage();
    return ((msg[1] & 0xFF) == META_END_OF_TRACK_TYPE) && (msg[2] == 0);
    }


    /** return if the given message is a meta tempo message */
    public static boolean isMetaTempo(MidiMessage midiMsg) {
    // first check if it is a META message at all
    if (midiMsg.getLength() != 6
        || midiMsg.getStatus() != MetaMessage.META) {
        return false;
    }
    // now get message and check for tempo
    byte[] msg = midiMsg.getMessage();
    // meta type must be 0x51, and data length must be 3
    return ((msg[1] & 0xFF) == META_TEMPO_TYPE) && (msg[2] == 3);
    }


    /** parses this message for a META tempo message and returns
     * the tempo in MPQ, or -1 if this isn't a tempo message
     */
    public static int getTempoMPQ(MidiMessage midiMsg) {
    // first check if it is a META message at all
    if (midiMsg.getLength() != 6
        || midiMsg.getStatus() != MetaMessage.META) {
        return -1;
    }
    byte[] msg = midiMsg.getMessage();
    if (((msg[1] & 0xFF) != META_TEMPO_TYPE) || (msg[2] != 3)) {
        return -1;
    }
    int tempo =    (msg[5] & 0xFF)
                | ((msg[4] & 0xFF) << 8)
                | ((msg[3] & 0xFF) << 16);
    return tempo;
    }


    /**
     * converts<br>
     * 1 - MPQ-Tempo to BPM tempo<br>
     * 2 - BPM tempo to MPQ tempo<br>
     */
    public static double convertTempo(double tempo) {
    if (tempo <= 0) {
        tempo = 1;
    }
    return ((double) 60000000l) / tempo;
    }


    /**
     * convert tick to microsecond with given tempo.
     * Does not take tempo changes into account.
     * Does not work for SMPTE timing!
     */
    public static long ticks2microsec(long tick, double tempoMPQ, int resolution) {
    return (long) (((double) tick) * tempoMPQ / resolution);
    }

    /**
     * convert tempo to microsecond with given tempo
     * Does not take tempo changes into account.
     * Does not work for SMPTE timing!
     */
    public static long microsec2ticks(long us, double tempoMPQ, int resolution) {
    // do not round to nearest tick
    //return (long) Math.round((((double)us) * resolution) / tempoMPQ);
    return (long) ((((double)us) * resolution) / tempoMPQ);
    }


    /**
     * Given a tick, convert to microsecond
     * @param cache tempo info and current tempo
     */
    public static long tick2microsecond(Sequence seq, long tick, TempoCache cache) {
    if (seq.getDivisionType() != Sequence.PPQ ) {
        double seconds = ((double)tick / (double)(seq.getDivisionType() * seq.getResolution()));
        return (long) (1000000 * seconds);
    }

    if (cache == null) {
        cache = new TempoCache(seq);
    }

    int resolution = seq.getResolution();

        long[] ticks = cache.ticks;
    int[] tempos = cache.tempos; // in MPQ
    int cacheCount = tempos.length;

    // optimization to not always go through entire list of tempo events
    int snapshotIndex = cache.snapshotIndex;
    int snapshotMicro = cache.snapshotMicro;

    // walk through all tempo changes and add time for the respective blocks
    long us = 0; // microsecond

    if (snapshotIndex <= 0
        || snapshotIndex >= cacheCount
        || ticks[snapshotIndex] > tick) {
        snapshotMicro = 0;
        snapshotIndex = 0;
    }
    if (cacheCount > 0) {
        // this implementation needs a tempo event at tick 0!
        int i = snapshotIndex + 1;
        while (i < cacheCount && ticks[i] <= tick) {
        snapshotMicro += ticks2microsec(ticks[i] - ticks[i - 1], tempos[i - 1], resolution);
        snapshotIndex = i;
        i++;
        }
        us = snapshotMicro
        + ticks2microsec(tick - ticks[snapshotIndex],
                 tempos[snapshotIndex],
                 resolution);
    }
    cache.snapshotIndex = snapshotIndex;
    cache.snapshotMicro = snapshotMicro;
    return us;
    }

    /**
     * Given a microsecond time, convert to tick.
     * returns tempo at the given time in cache.getCurrTempoMPQ
     */
    public static long microsecond2tick(Sequence seq, long micros, TempoCache cache) {
    if (seq.getDivisionType() != Sequence.PPQ ) {
        double dTick = ( ((double) micros)
                       * ((double) seq.getDivisionType())
                       * ((double) seq.getResolution()))
                       / ((double) 1000000);
        long tick = (long) dTick;
        if (cache != null) {
        cache.currTempo = (int) cache.getTempoMPQAt(tick);
        }
        return tick;
    }

    if (cache == null) {
        cache = new TempoCache(seq);
    }
        long[] ticks = cache.ticks;
    int[] tempos = cache.tempos; // in MPQ
    int cacheCount = tempos.length;

    int resolution = seq.getResolution();

    long us = 0; long tick = 0; int newReadPos = 0; int i = 1;

    // walk through all tempo changes and add time for the respective blocks
    // to find the right tick
    if (micros > 0 && cacheCount > 0) {
        // this loop requires that the first tempo Event is at time 0
        while (i < cacheCount) {
        long nextTime = us + ticks2microsec(ticks[i] - ticks[i - 1],
                            tempos[i - 1], resolution);
        if (nextTime > micros) {
            break;
        }
        us = nextTime;
        i++;
        }
        tick = ticks[i - 1] + microsec2ticks(micros - us, tempos[i - 1], resolution);
        if (Printer.debug) Printer.debug("microsecond2tick(" + (micros / 1000)+") = "+tick+" ticks.");
        //if (Printer.debug) Printer.debug("   -> convert back = " + (tick2microsecond(seq, tick, null) / 1000)+" microseconds");
    }
    cache.currTempo = tempos[i - 1];
    return tick;
    }


    /**
     * Binary search for the event indexes of the track
     *
     * @param tick - tick number of index to be found in array
     * @return index in track which is on or after "tick".
     *   if no entries are found that follow after tick, track.size() is returned
     */
    public static int tick2index(Track track, long tick) {
    int ret = 0;
    if (tick > 0) {
        int low = 0;
        int high = track.size() - 1;
        while (low < high) {
        // take the middle event as estimate
        ret = (low + high) >> 1;
        // tick of estimate
        long t = track.get(ret).getTick();
        if (t == tick) {
            break;
        } else if (t < tick) {
            // estimate too low
            if (low == high - 1) {
            // "or after tick"
            ret++;
            break;
            }
            low = ret;
        } else { // if (t>tick)
            // estimate too high
            high = ret;
        }
        }
    }
    return ret;
    }


    public static class TempoCache {
        long[] ticks;
    int[] tempos; // in MPQ
    // index in ticks/tempos at the snapshot
    int snapshotIndex = 0;
    // microsecond at the snapshot
    int snapshotMicro = 0;

    int currTempo; // MPQ, used as return value for microsecond2tick

    private boolean firstTempoIsFake = false;

    public TempoCache() {
        // just some defaults, to prevents weird stuff
        ticks = new long[1];
        tempos = new int[1];
        tempos[0] = DEFAULT_TEMPO_MPQ;
        snapshotIndex = 0;
        snapshotMicro = 0;
    }

    public TempoCache(Sequence seq) {
        this();
        refresh(seq);
    }


    public synchronized void refresh(Sequence seq) {
        ArrayList list = new ArrayList();
        Track[] tracks = seq.getTracks();
        if (tracks.length > 0) {
            // tempo events only occur in track 0
            Track track = tracks[0];
            int c = track.size();
        for (int i = 0; i < c; i++) {
            MidiEvent ev = track.get(i);
            MidiMessage msg = ev.getMessage();
            if (isMetaTempo(msg)) {
            // found a tempo event. Add it to the list
            list.add(ev);
            }
        }
        }
        int size = list.size() + 1;
        firstTempoIsFake = true;
        if ((size > 1)
        && (((MidiEvent) list.get(0)).getTick() == 0)) {
        // do not need to add an initial tempo event at the beginning
        size--;
        firstTempoIsFake = false;
        }
        ticks  = new long[size];
        tempos = new int[size];
        int e = 0;
        if (firstTempoIsFake) {
        // add tempo 120 at beginning
        ticks[0] = 0;
        tempos[0] = DEFAULT_TEMPO_MPQ;
        e++;
        }
        for (int i = 0; i < list.size(); i++, e++) {
            MidiEvent evt = (MidiEvent) list.get(i);
        ticks[e] = evt.getTick();
        tempos[e] = getTempoMPQ(evt.getMessage());
        }
        snapshotIndex = 0;
        snapshotMicro = 0;
    }

    public int getCurrTempoMPQ() {
        return currTempo;
    }

    float getTempoMPQAt(long tick) {
        return getTempoMPQAt(tick, -1.0f);
    }

    synchronized float getTempoMPQAt(long tick, float startTempoMPQ) {
        for (int i = 0; i < ticks.length; i++) {
        if (ticks[i] > tick) {
            if (i > 0) i--;
            if (startTempoMPQ > 0 && i == 0 && firstTempoIsFake) {
            return startTempoMPQ;
            }
            return (float) tempos[i];
        }
        }
        return tempos[tempos.length - 1];
    }

    }
}